Controllable pitch propeller



Feb. 14, 1939. 1.3 m. 2,147,078

CONTROLLABLE PI'TcH PROFELLER" Filed Aug. 5, 1935 3 Sheets-Sheet 2 F ch.

T. B ARISH CONTROLLABLE PITCH PROPELLER Filed Aug. 5, 1935 3 Sheets-Sheet 3 untam- I v 'atented F'eb 14, 1939- UNITED STATES 2.14am V -M Pri'cn mom 7 r.

PATENT OFFICE Thomas Barlsh, Nr-Ysi to Aviation Manufacturing Corporation, Chicago, 111., a corporation or Delaware,

' "shaman August 5,1935. Serial No. 34.631

14 Claims. (01.170-163) The invention relates to controllable pitch pro- ;ellers for aircraft.

One object of the invention is to provide a con- ;rollable .pitch propeller for aircraft. in which a :entrifugally responsive weight for effecting pitch changes is mounted in the blade.

- Another object of the invention is to provide a :ontrollabie pitch propeller for aircaft in which ;he centrifugally responsive weight and fluid pressure means for effecting pitch-changes are both.

disposed in the propeller blade.

Another object of the invention is to provide. a controllable pitch propeller in which the centrifugal force of a weight effects pitch-changes of the blade through intermediate speed reduction 7 gearing.

Another object of the invention is to provide Improved pitch-changing means whereby the pitch of the blades may be varied to any desired degree within the desired predetermined range.

Another object of the invention is to provide a variable pitch propeller, which is simple in construction and efiicient in operation.

Other objects of the invention will appear from I the detailed. description.

The invention consists in the several novel features hereinafter set forth and more particularly defined by claims at the conclusionhereof.

In the drawings: Fig. 1 is a section through one which the weight moves, and the shaft operated by the weight. Fig. 7 is a perspective ofthe thrust-collar or head which is fixed to the inner end of the blade and carries the planetary pinions which are driven by the shaft in the weight and carries a gear meshing with an interconnecting' gear "tor equalizing the pitch oi all the blades of the propeller. Fig. 8 is an elevation, partly inv section, of a-three-blade propeller embodying the invention. Fig. 9 is a section ofa blade and mechanism embodying a modified form of the invention- I v Q v The invention-is exemplified in alpropeller. which is fixed to and driven by a shaft 10,- which is iournalcd in abearing II, which is carried by a stationary case or housing l2. A hub It is splined to the shaft I and suitably fixed-thereon by wedge collars l4 and lock-rings l5, l5. These parts may be of any suitable construction, as well understood in the art.

The hub I3 is provided with an integral tubular 'extension [6 for each of the propeller blades l I.

The blades and pitch-change mechanism are the same for each of the blades, so that a description of one is applicable t all. A collar or head I8 is secured, by a buttre rew-thread, to the inner end of the hollow shank of the propeller blade II. The blade is rotatable on its own axis in the extension IS of the hub and. is confined against radial movement in the hub by a series of thrustbearings IQ of the ball type. A screw-ring threaded into and locked in the outer end of extension IS, serves as a thrust-member for the outer races of said bearings. The-outerend oi head [8 abuts against the inner of the inner series of races of said bearings sorthe outward thrust of the blade will be through bearings l9 and ring 20 to the hub-extension l6. An integral annulus 2! on the inner end of head i8 is journaled in a ball-bearing 22, which is carried by the hub, to permit rotation of the blade I! and head I 8 on their own axis forpitch-adiustment.

The pitch-changing mechanism comprises a weight 23, which is movable outwardly by centrifugal force when the propeller is operated.

A This weight is confined in a radially disposed cylinder 24, which is concentrically fitted in the hollow shank. of the blade l1, and issuitably locked thereto by suitable studs 25, whichpass through notches in a fiange at the inner end of the cylinder. The'buter end of cylinder 24 is closed bya head 28. On the outer end of the weight a piston 21 is provided. This piston is fitted to the bore of the cylinder 24 and is provided 'with piston-rings 28 so the weight will be operable inwardly against centrifugal force by fluid under pressure in the outer end of the cylinder. The combined weight and piston 23, '21 is movable in the cylinder 24 and radially of the propeller. This weight hasinclined or helical ribs 29 on its inner end which interfit with correspondingly inclined outward and longitudinally of the cylinder by centrifugal force, or inwardly by fluid under pressure,

there will be relative rotary and sliding movement between the weight and the blade in which the cylinder '24 is s zed. l v

, extension 2i of the head l3 and its outer end joumaled in an inwardly extending bearing 34 on the cylinder-head 26. The outer periphery of shaft 32 is provided with straight longitudinal ribs 35, which interfit with ribs 36 on the weight 23 to form a spline-connection for rotating the shaft by the weight while permitting radial move-1 ment of the weight. A pinion3'l is formed on shaft 32 adjacent its inner end and meshes with a series of planetary pinions 38 which are journaied in and bodily rotatable with'the head I9 and the blade-fixed to the head. Pinions 38 mesh with a ring-gear 3,9, which is fixedly held in the hub extension l3 by keys 40. A spacing-ring 4| is interposed between the gear-ring 39 and the outer race of the innermost thrust-bearingv I9.

When the propeller is revolving, weight 2.3 is subjected to centrifugal force, so it can move outwardly in the cylinder 24 and, through the helical spline-connection 29, 30 between the weight andthe cylinder 24, it will be rotated relatively to the cylinder and blade by such force. The shaft 32, through the spline-connection 35, 36, from the rotary moment of the weight will be rotated with the weight so it will turn pinion 31. Pinion 31 will rotate the planetary pinions 38,

,which mesh with the gear-ring 39, which isflxed in the hub, with the result that the pinions 38 will, by reason of their engagement with ring 39, move bodily and slowly rotate the head. l8 and blade I! and cylinder 24 in the hub. This rotation of the blade and cylinder will be less in deree than the rotation of the weight 23, and the shaft 32, so that fine pitch-changes can be ef fected. The planetary gearing serves as movement reducing means for the rotation of the propeller around its axis responsive to the longitudinal and rotary movement of the weight. In the rotation of the blade by the weight, the cylinderdiiferentially follows the rotative movement, and

- thisvalso reducesthe speed of the pitch-changes.

Inward movement of the weight effects reverse rotation of the blade and gearing. In practice, the centrifugal force ofthe weight is preferably applied to effect pitch increase, because of the greater force required to overcome the aerodynamic and centrifugal moments of the blade.

Fluid under pressure is used for shifting the weight 23 toward the axis of the drive-shaft against centrifugal force and controlling the pitch-changes of the'blades in the opposite direction to that produced by outward movement thereof, preferably to decrease the -pitch. For this purpose, a duct 42, formed in. the hub l3, leads from an annular. groove 43in the hub to the inner end of each hollow shaft 32. Suitable fluid, usually oil, under pressure from any suitable source, such as a booster-pump, (not shown) is connected to delivery the fluid through a duct 44' in housing l2 into an annular chamber 44 in a fixed ring 43' which extends around the hub l3. 'Iheinner end of theshaft 32 is fltted ins. stuff ing-box 43; From the innerend of the hollow shaft 32, the fluid'flows outwardly through the shaft, and ports 41in the shaft and P rts 43; into the outer end of the cylinder 24,-to exert pressure on the outer side of the piston '21, and force the'weight inwardly againstcentrifugai force. The supply of fluid under pressure for controll-v ing the inward movements of the centrifugal Weisht 33 and piston 23, may be controlled by any suitable mans, as well understood in thearti gear-ring 39, will cause the pinions 38 to rotate Any oil which may leak past the piston 21 will pass through the inner end of the cylinder 24, the central portion of head l3, bearing. 33, into a well 49 in the hub'and around stuffing-box 46. A return duct'50, indicated by dotted lines in Fig. 1, returns the oil from well 49 to an annulargroove 5| in the hub, which delivers the oil to a returnduct 52 in the housing l2. Resilient rings 53 are provided in the hub l3 to prevent escape of oil between the hub and oil-ring 45, and to separate the oil in the supply and return-ducts. 7

Each of the blades is provided with pitchchanging mechanism, as described, and this is applicable to a propeller with any number of 3 blades. The head N3 of each blade is formed at its inner end and inwardly of pinions 33 with a bevel gear 53, which meshes with a bevelled and interconnecting bevel'gear-ring 54, which is journaled on a ball-bearing 55 around the hub I3.

This bevelled gear-ring 54 equalizes the adjustment of the blades around'their respective axes to insure uniform pitch-setting of all of the blades.

In operation, fluid underrcontrolled pressure from the oil-pump, is delivered to the outer end of. each cylinder 24 through duct 44', ring 45, groove 43, duct 42, the bore of hollow shaft 32, and ports 41, 48. Preferably, the blades are set at the minimum predetermined pitch desired when the weights 23 are held at the inner ends i of cylinders 24, so that the movement of the weights 23 by centrifugal force while the propeller is in operation, will increase the pitch of the blades. At such time, fluid under pressure serves to hold the weights at the inner ends of i the cylinders against centrifugal force according to the low pitch desired. When it is desired to increase the pitch, the pilot will manipulate the conthe pinion 31 thereon to rotate around the'axis of the blade. The. pinion 31, meshing with'the planetary pinions 38, which mesh with the fixed on their own axes and to move bo y around the axis of the shaft 32 and the bade. This movement of the gearing will impart a corresponding rotary movement to head l9, the blade I1, and the cylinder 24, which are allflxed-together. As a result, each blade will be rotated for pitch-increase responsively to the centrifugal force of its applied weight 23 under control of fluid under pressure, through the planetary reduction gearins.- As the result of the outward \movement of each weight-23 by centrifugal force, its rotation will operate the shaft 32 and the sear- .ing to Trotateeach blade II a distance proportionateto' the extent of the outward movement of the weight, which may be checked at any point desired by control of the supply of fluid under pressure. In effecting this pitch increase, f the weight, and the blade will rotate differentially in the same direction as effected through the 7| planetary gearing and the helical spline-connection betweenthe weight and the cylinder fixed to the blade, the blades rotatingat -a propor-,

melyleas deuce wdght 21 shaft ta. This .oonstru' ction makes .it possible II to accurately and positively control. the pitch of the blades due to the diiferentlal rotation of the weight and the blade and the intermediate gearing. It also makes it possible to use centrifugal weights in the shank of the blades, which is an advantageous and desirable place for them.

A characteristic of using a centrifugal weight which moves radially in the hollow shank of a blade to increase the bladeepitch, is that the centrifugal force varies proportionately to its movement away from the axis of the propeller shaft, so that the greater resistance to pitch increase under higher pitch angles which results weight inwardly until the pitch has been reducedto the desired degree through the reverse operatheir adjustable stud-connection 25 with the.

from increase of centrifugal and aerodynamic.

tion of weight and gearing. The bevelled gearring 54, which meshes with the bevelled gears 53 on the collars l8 of all of the blades, equalizes and synchronizes the pitch-changes of all the blades of the propeller. By rotating any ofthe cylinders 24 in=the blades 11, as permitted by blades, the latter may be'accurately set so that ailthe blades will have a uniform pitch. A removable head 58 is provided at the front of-the hub l3 for the insertion and removal of gear 54 and its bearing 55. The cylinder, centrifugal weight, and its shaft, can bereadily assembled in the bore of a hollow metal propeller blade. The gearing carried by the thrust-head or member l8 on the blade can be assembled with the blade after the cylinder and weight have been assem-- bled, thus providing a construction which can be readily assembled; I

In the modification of the invention illustrated in Fig. 9,"themechanism is .of the same construction previously described, except that the centrifugal weight is splined to the cylinder-fixed to the blade for slidable movement in, and conjoint rotation with, the blade and is helically splined to the gear-shaft, so that it will slide and rotate relatively to the shaft. The piston 23 is slidably splined to the cylinder 24' by straight interfitting ribs 3i) onthe cylinder and ribs 29 on the weight. The pinion shaft 32 is ment on the shaft 32 to drive the pinion 31' on said shaft to operate the planetary gears 38', which are carried by the head l8, so that the blade ll, cylinders 24, and'weigh't 23 will .be rotated on their own axes, by the planetary movement of'the pinions. 38 and relatively to the shaft 32'. In other respects, the operation of the modification will be the same as that previously described. In this modified construction, there is diiferential rotation of the pinion-shaftnand the weight, cylinder and blade, and conjoint rotation of the blade, cylinder and weight. The

same result in compactness, advantages in con-- struction, location of theshifting devices in the shank of the blade, 'eificiency and accuracy in pitch-adjustment, are attained.

The invention exemplifies a controllable pitch- 7 propeller embodying pitch-changing mechanism comprising centrifugal weights, which are mounted in the hollow shanks of the blades; in which the centrifugal-weights are guided in the blades for greater effectiveness as required by themcrease of the aerodynamic and centrifugal moments of the blades when set at high pitches;

in which hydraulically. and centrifugally con-' trolled pitch-change devices are mounted in the shanks of the blades; in which reduction-gearing is interposed between the centrifugal weight and the blade .for accurate and gradual pitch varia-.

tion; in which centrifugally controlled weights and associateddevlces can be readily assembled in, and disassembled from, the blades; and which is eflicient in operation and simple in construction.

The invention is not to be understood as restricted to the details set forth, since these may be modified within the scope of the. appended claims, without departing from" the spirit and scope of the invention.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent is:

1. In a controllable pitch propeller, the combination of a' hub, a propeller-blade rotatably mounted in-the hub for pitch-variation, a weight mounted to move in the shank of the blade, movable by centrifugal force, and means for rotating the blade from the weight for pitch-variation,

comprising a radial rotatable shaft and a slidable spline-connection between the weight and the shaft and reduction gearing between the shaft and the blade.

2. In. a controllable pitch propeller, the combination of a hub, a propeller-blade rotatably mounted in the hub forpitch-variation, a weightmounted to move in -the shank of the blade, movable by centrifugal force, and means ,for rotating the blade from the weight for pitch-variation,

' comprising a radial rotatable shaft and a slidable and helical spline-connection between ,the weight and the shaft and reduction gearing'between the shaft and the blade.

3'. In a controllable pitch propeller, the combination of a hub, a propeller-blade rotatably mounted in the hub for pitch-variation, a radial .cylinder in the shank of the blade, a weight mounted to slide in the cylinder and movable by centrifugal force, a piston on the weight and in the cylinder, means for rotating the blade from 4. In a controllable pitch propeller, the com-' bination of a hub, a propeller-blade rotatably mounted in the hub for pitch-variation, a weight mounted in the blade and movable by centrifugal force, a spline-connectionbetween the weight and I a the blade, a' rotatable shaft, and a spline-connection between the weight and the shaft, one of saidspline connectionsbeing helical and gearing driven by the shaft to rotate the blade.

5. In a controllable pitch propeller, the combination of a hub, a propeller-blade rotatably mounted in thehub for pitch-variation, a weight mounted in the blade and movable by centrifugal force, a spline-connection between the weight and the blade, a rotatable shaft, a slidable splineconnection between the weight and the shaft-one of said spline-connections being helical, and reduction-gearing operable by the shaft and connected to rotate the blade.

6. In a controllable. pitch propeller, the combination of a hub, a propeller-blade rotatably mounted in the hub for pitch-variation,"'a' weight mounted in" the blade and movableby centrifugal force, a helical spline-connection between the weight and the blade, a rotatable shaft, and a spline-connectionrbetween the weight and the 8. In a controllable pitch propeller, the combi- I nation of a-hub, a propeller-blade rotatably mounted in the -hub for pitch-variation, and

meansfor rotating the blade to vary its pitch,

comprising a weight radially movable in the shank of the blade by centrifugal force, a splineconnection between the weight and the blade, and

a central element in the weight and a spline-connection between the weight and said element, one of said spline-connections being helical and reduction'gearlng between said elements andthe blade.

9. In a controllable pitch propeller, the combination of a hub, a propeller-blade rotatably mounted in .the hub .for'pitch-variation, and

means for rotating the blade to vary itspitch,

comprising a weight radially movable in the shank of the blade by centrifugal force, a splineconnection between the weight and the blade, a central element in the weight and a spline-connection between the weight and said element, one of said spline-connections being helical, and fluid pressure means for shifting the weight against centrifugal force, comprising a duct extending through said element.

- 10. In a controllable pitch propeller, the combination of a hub, a propeller blade rotatably mounted in the hub forpitch variation and provided in its shank with a radial cylinder, a weight movably mounted in the cylinder, movable by centrifugal force and rotatable around the axisof the blade, a radial rotatable shaft extending through the weight and rotatable by the weight, for rotatthe blade to change itspltch in one direction.

a piston fitted in the cylinder for shifting the weight against centrifugal force, and means for delivering afluid under pressure into the cylinder, for shifting the piston and weight against centrifugal force and rotating the shaft tochange the pitch of the blade in the other direction.

11. In a controllable-pitch propeller, the combination of ahub, a propeller blade rotatably mounted in the hub for pitch variation and against radial movement and provided with 'a radial cylinder, a radial rotatable shaft concentrically mounted in the hub, a radially slidable weight and piston splined to the cylinder and to radial cylinder, a radial rotatable shaft concentrically mounted in the hub, a radially slidable weight and piston splined tothe cylinder and to the shaft-and rotatable around the axis of the shaft and blade, said shaft being rotatable by the weight, and gearing operable by rotation of the shaft for rotating the blade on its own axis for pitch variation.

13; In a controll bination of a hub, a propeller blade rotatably mounted in the hub for pitch variation" and against radial, movement and provided with a radial cylinder, a radial rotatable shaft concentrically mounted in the hub, a radially slidable able patch propelled, the comweight and piston splined to the cylinder and to" the shaft and rotatable around the axis of the shaft and blade, said shaft being rotatable by the weight, and planetary gearing operable by the rotation of the shaft for rotating the blade on its own axis for pitch variatioh.

14. In a controllable pitch propeller, the combination of a hub, a propeller blade rotatably mounted in the hub for pitch variation and against radial movement and provided in its shank with a radial cylinder, a weight radially slidable in and splined to the cylinder and rotatabl around the axis of the blade, a piston in the cylinder movable with the weight and a radial shaft rotatable around the axis of the blade and rotatable by the weight, connected to rotate the blade onfits own axis for pitch variation.

' moms BARI SJH. 

